arXiv subjects

M. Pasquale

Publications and source records attributed to M. Pasquale.

4 recordsLinked to original sources

arXiv2020

A comparison of two different mechanisms for deterministic spin orbit torque magnetization switching

In this article we analyze by modeling two possible mechanisms for magnetization switching using spin orbit torques, which have been reported to cause field-free deterministic switching in experiments. Here we compare the field-free magnetization switching due to a tilt of the anisotropy direction against the use of an antiferromagnetic bias field. Simple results obtained analytically show that a bias field not only causes the magnetization reversal but also reduces the corresponding energy barrier. The critical current required for magnetization switching is analyzed on the basis of a macrospin model. It is shown that although the field-free deterministic switching caused by a tilt of the anisotropy is more robust than the bias field in the development of memory elements, a compromise between requirements has to be adopted when selecting the parameters for specific applications.

cond-mat.mes-hall↗

arXiv2018

Spincaloritronic measurements: a round robin comparison of the longitudinal spin Seebeck effect

The rising field of spin caloritronics focuses on the interactions between spin and heat currents in a magnetic material; the observation of the spin Seebeck effect opened the route to this branch of research. This paper reports the results of a round robin test performed by five partners on a single device highlighting the reproducibility problems related to the measurements of the spin Seebeck coefficient, the quantity that describes the strength of the spin Seebeck effect. This work stimulated the search for more reproducible measurement methods through the analysis of the systematic effects.

cond-mat.mes-hall↗

arXiv2017

Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method

The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was $(1.143\pm0.007)\cdot 10^{-7}$ Vm/W and $(1.101\pm0.015)\cdot 10^{-7}$ Vm/W with the heat flux method and $(2.313\pm0.017)\cdot 10^{-7}$ V/K and $(4.956\pm0.005)\cdot 10^{-7}$ V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.

cond-mat.mes-hall↗

arXiv2013

Influence of sample geometry on inductive damping measurement methods

We study the precession frequency and effective damping of patterned permalloy thin films of different geometry using integrated inductive test structures. The test structures consist of coplanar wave guides fabricated onto patterned permalloy stripes of different geometry. The width, length and position of the permalloy stripe with respect to the center conductor of the wave guide are varied. The precession frequency and effective damping of the different devices is derived by inductive measurements in time and frequency domain in in-plane magnetic fields. While the precession frequencies do not reveal a significant dependence on the sample geometry we find a decrease of the measured damping with increasing width of the permalloy centered underneath the center conductor of the coplanar wave guide. We attribute this effect to an additional damping contribution due to inhomogeneous line broadening at the edges of the permalloy stripes which does not contribute to the inductive signal provided the permalloy stripe is wider than the center conductor. Consequences for inductive determination of the effective damping using such integrated reference samples are discussed.

cond-mat.mes-hall↗